1. Field of the Invention
The present invention relates to structures for treating an object by a laser beam, and more particularly to an optical system for a laser beam structure which includes a parity corrected lens.
2. Background Art
Structures including a laser beam and optical elements have been used to irradiate an object for treatment such as quenching, alloying, ablating and the like. In U.S. Pat. No. 4,315,130 issued Feb. 9, 1992 to Inagaki et al. entitled "Method of Treating Object By Laser Beam and Apparatus Therefor", a laser treatment apparatus is disclosed in which the laser beam emitted from a laser for irradiating an object is divided into a plurality of fractional beams and the fractional beams are reflected towards the object to be irradiated with uniform energy distribution. A plurality of different configurations of reflecting means are shown.
In U.S. Pat. No. 4,822,975 issued Apr. 18, 1989 to Torigoe entitled "Method and Apparatus for Scanning Exposure", an apparatus is disclosed for scanning exposure with a pulsed laser beam. A pattern of a first member is irradiated by the pulsed laser beam and the pattern of the first member is projected onto a second member. During the pattern projection the first and second members are moved in a predeterminedly synchronized relation, while the irradiation or pulse emission and the movement of the first and second members are co-ordinated with each other, whereby a uniform amount of exposure is ensured on the second member.
In U.S. Pat. No. 4,661,679 issued Apr. 28, 1987 to Pardee entitled "Semiconductor Laser Processing With Mirror Mask", a semiconductor processing technique is provided for reacting with the surface of a semiconductor wafer substrate only along a predetermined pattern without a pass-through mask. Excimer pulsed ultraviolet laser radiation is reflected by a mirror having a selective pattern thereon to direct laser radiation only along a predetermined pattern onto the substrate surface as determined by the selective mirror pattern to selectively activate designated areas of the substrate.
U.S. Pat. No. 5,109,149 issued Apr. 28, 1992 to Leung entitled "Laser Direct-Write Integrated Circuit Production System" discloses a laser, direct-write system for making personalized custom or semi-custom integrated circuits with a very fast turnaround time. The system includes a method and apparatus for high precision scanning of a submicron laser spot. The laser beam is scanned at the entrance of a beam expander. The beam expander reduces the scan angle and error produced by a mechanical scanning device such as a rotating polygonal mirror. The smaller scan angle at the output of the beam expander matches well with the projection optics of a laser, direct-write integrated circuit production system.
U.S. Pat. No. 3,951,546 issued Apr. 20, 1976 to Markle entitled "Three-Fold Mirror Assembly For A Scanning Projection System" describes a three-fold mirror array for a scanning projection system to permit placing the object and image of an annular reflective projection system in an orientation which facilitates scanning and yields an image symmetry identical to that obtained with contact printing in which three folding flats are combined with an annular field projection system. The three folding flats are incorporated in a monolithic assembly having a 90.degree. groove on one side and a fold surface perpendicular to the other folding surfaces on the other side of the assembly thereby permitting a simple pivoting scanning mechanism to be used for scanning a field larger than the narrow annular field available in the projection system.